The present invention relates to a connector which is fitted to an aperture portion of a container which stores a liquid such as, for example, semiconductor high purity chemicals or general chemicals or the like and which is used for taking out and supplying the stored fluid, and in particular relates to such a connector which has a plurality of conduits.
A liquid such as, for example, semiconductor high purity chemicals or general chemicals or the like is filled into a container in the production facility, and is despatched in the state with lids (not shown in the figures) covering over aperture portions formed in this container.
When the liquid which is stored in this container is to be taken out therefrom, as shown in FIG. 6, first the lids which covered over aperture portions 1a and 1b of the container 1 are taken off therefrom, and a plug 3a to which a syphon tube 2 is connected and a plug 3b to which no such syphon tube is connected are fitted to these aperture portions 1a and 1b respectively.
And a socket 4a to which is connected a liquid transport hose 5 is connected to the plug 3a while a socket 4b to which a gas transport hose 7 is connected to the plug 3b, and the liquid in the container 1 is sucked up to the plug 3a via the syphon tube 2 by a pump (not shown in the figure) and is conducted into the liquid transport hose 5 which is connected to the socket 4a. 
At this time gas such as nitrogen or the like is supplied through a gas transport hose 7 which is connected to the other socket 4b, in order that no vacuum should build up in the container 1.
On the other hand, as a technique for one-touch connection of the sockets 4a and 4b to the plugs 3a and 3b, there is a per se known connector which has been disclosed in Japanese Patent Laying-Open Publication 7-277400.
This connector comprises a lock mechanism in which, along with hole portions being formed at intervals around the circumferential direction of a wall portion which defines a concave portion on the side of the socket, latching balls are received in these hole portions so as to be able to enter into and to come out of the concave portion, and, by a sleeve which is disposed around the outer peripheral surface of the concave portion being made to slide in the axial direction, the latching balls are caused to be projected from the hole portions into within the concave portion, thus engaging the latching balls into an engagement groove which is formed around the outer peripheral surface of a plug which comprises a liquid conduit and which is engaged into the concave portion.
However it sometimes happens that, when taking liquid out of the container 1, circulation is performed as shown in FIG. 7(a) so as to pass the liquid through a filter in order to eliminate contaminants and the like.
In this case, with the above described single conduit connectors 6a and 6b, the problem has arisen that the system becomes rather complicated, since, along with connecting the connector 6a for taking out the liquid and the connector 6b for feeding in gas by a piping system 10 for circulation, it has been necessary to provide a valve 9 for opening and closing a conduit within this piping system 10 for circulation.
Furthermore, since the surface of the liquid within the container 1 becomes ruffled (which is undesirable) when liquid drips from the connector 6b for feeding in gas, therefore this ruffling must be suppressed, and accordingly during such circulation another syphon tube 2 has been connected to the connector 6b for feeding in gas as well.!!
However, if a syphon tube 2 is connected to the connector 6 for feeding in gas, then, although it is possible to suppress the generation of ruffles upon the surface of the liquid within the container 1, the particular problem described below occurs.
Namely, when circulation has been completed and the liquid is to be taken out of the container 1, the valve 9 is closed, and nitrogen is fed in through the connector 6b for feeding in gas in order to prevent the build up of vacuum; but, since the syphon tube 2 dips in below the surface of the liquid in the container 1, at this time the nitrogen bubbles out below the surface of the liquid, and in some cases this may cause an undesirable reaction.
In order to avoid this problem, the nitrogen may be supplied into the container 1 at a position higher than the surface of the liquid therein, but in order to do this it is necessary to remove the syphon tube, if the connector 6b is a single conduit type connector.
On the other hand, if both of the plugs 3a and 3b and the sockets 4a and 4b are made as double connectors which have both a liquid conduit and a gas conduit, as shown in FIG. 7(b), then the above described problem is completely eliminated. Furthermore, if these plugs and sockets which are provided with a plurality of conduits are structured as connectors which are connected together via locking mechanisms of the above described type, then it also becomes possible to perform a one-touch operation for connecting the plugs with the sockets, and the quality of the product is further enhanced.
However, if not only a liquid conduit but also a gas conduit is to be formed in the interior of the plug, then due to this the external diameter of the plug is increased, which invites increase of the size of the locking mechanism, and moreover the internal structure of the plug becomes more complicated, which makes its process of manufacture more difficult, so that the new problem of increase of cost arises.
Accordingly, the present invention has as its objective the proposal of a connector whose usability is excellent due to its being provided with a plurality of conduits, and which is easy to manufacture at low cost.
The connector according to the present invention includes a plug which closes an aperture portion formed in a container and a socket which is connected to a hose, and, by connection together of this plug and this socket, mutually communicates together main conduits which are formed in this plug and socket, and sub-conduits which are formed in this plug and socket; and this plug includes a plug portion to which the socket is engaged and which maintains the connection state to the socket, with this plug portion having the main conduit in its internal portion while it has the sub-conduit externally.
And since, according to the present invention as described above, in the same manner as in the prior art, only a single conduit is provided to the plug portion to which the socket is engaged, therefore it is possible to avoid increase in the size of the plug portion and increase of complication of its internal structure.
Accordingly it is possible to provide a connector whose usability is excellent due to its being provided with a plurality of conduits, and which is easy to manufacture at low cost.